Flexible deployable rotor system



Aug. 1 1967 P. F. GIRARD FLEXIBLE DEPLOYABLE ROTOR SYSTEM 4 Sheets-Sheet 1 Filed March 16, 1965 INVENTOR. PETER F. GIRARD Knox & 141101:

g- 1967 P. F. GIRARD 3,333,643

FLEXIBLE DEPLOYABLE ROTOR SYSTEM Filed March 16, 1965 4 Sheets-Sheet 2 I INVENTOR PETER F. GIRARD P. F. GIRARD Aug. 1, 1967 FLEXIBLE DEPLOYABLE ROTOR SYSTEM Filed March 16, 1965 4 Sheets-Sheet 3 INVENTOR. PETER F. GIRARD Fig.9

g 1, 1967 P. F. GIRARD 3,333,643

FLEXIBLE DEPLOYABLE ROTOR SYSTEM Filed March 16, 1965 43Sheets-Sheet 4 Fig. l5

INVENTOR. PETER F. GIRARD BY mmsscw United States Patent 3,333,643 FLEXIBLE DEPLOYABLE ROTOR SYSTEM Peter F. Girard, La Mesa, Califi, assignor to The Ryan Aeronautical Co., San Diego, Calif.

Filed Mar. 16, 1965, Ser. No. 440,136 12 Claims. (Cl. 17016ll.11)

ABSTRACT OF THE DISCLOSURE The rotor has flexible blades and collapsible structure for stowage in a minimum space, the assembly being self-deploying upon release to an initial partially open position in which built-in vanes start the rotor spinning due to air flow in falling, the rotor blades being released in stages by mechanism responsive entirely to rotational speed so that deceleration is gradual; when fully deployed the rotor is directionally controllable and is selfgoverning to a controlled rate of descent.

The present invention relates to aerial drop means and more specifically to a flexible deployable rotor system.

The most common aerial drop delivery means is the parachute, which has been developed in many forms. Substitute devices of more compact form have been devised which use rotors, either freely rotating or driven to a limited degree. One particular type of rotor uses rigid blades hinged to a central hub and is rather cumbersome even when folded due to the size of rotor blade necessary to support a certain load. Another type has semi-rigid blades which are stored in rolled form and extend by mechanical or centrifugal means to a radius dependent on the rotational speed. Neither type has any great degree of control over rate of descent under varying conditions, or control over direction of drift during descent and, if any sequencing is involved in the operation, timing means or power sources are required.

The primary object of this invention is to provide a rotor system in which the rotor itself is fully flexible and can be folded into a very small space, yet is rapidly deployable to a fully extended, aerodynamically self-sustaining configuration.

Another object of this invention is to provide a rotor system wherein the deployment is sequenced to minimize shock on the rotor and payload and, after initial release,

' is actuated through the sequence entirely by the surrounding air flow during free fall, without any power sources, timing devices, or similar means.

Another object of this invention is to provide a rotor which is self-adjusting and balancing to maintain a substantially constant rate of descent.

Another object of this invention is to provide a rotor system which is capable of gliding, in addition to vertical descent, and has means for directional control to facilitate landing in a selected area, stability being enhanced by directional guide means coacting with the rotor.

A further object of this invention is to provide a rotor system adaptable to handling a variety of payloads dropped from aircraft, or for recovery of missile parts, capsules, or space vehicles after their re-entry into atmosphere, the glide capability of the system being especially useful in the latter instances to simplify recovery.

In the drawings:

FIGURE 1 is a diagrammatic view of the rotor system stowed on a payload in the drop condition;

FIGURE 2 is a diagrammatic view of the rotor in the initial extraction position;

FIGURE 3 illustrates the secondary spin-up stage;

FIGURE 4 illustrates the rotor fully open;

FIGURE 5 is a top plan view of the rotor;

FIGURE 6 is an enlarged sectional view taken on line 6-6 of FIGURE 5;

3,333,643 Patented Aug. 1, 1967 FIGURE 7 is a top plan view of the payload and extended stabilizing fins;

FIGURE 8 is an enlarged sectional view taken on line 8-8 of FIGURE 5;

FIGURE 9 is a view taken on line 99 of FIGURE 8;

FIGURE 10 is a fragmentary sectional view taken on line 10-10 of FIGURE 8;

FIGURE 11 is a sectional view taken on line 11--11 of FIGURE 8;

FIGURE 12 is an enlarged sectional view taken on line 12-12 of FIGURE 8;

FIGURE 13 is a sectional view taken on line 1313 of FIGURE 12;

FIGURE 14 is a fragmentary sectional view taken on line 14-14 of FIGURE 11; and

FIGURE 15 is a diagram illustrating the rotor flare action for landing.

Rotor and deployment system The rotor 10 itself is of flexible sheet material, such as plastic, plasticized or rubberized fabric, or similar nonporous material with suitable strength characteristics. As illustrated, the rotor 10 has three blades 12, although any other convenient number may be used, each blade having a widened inner or root portion 14. The rotor has a central hub 16 with pitch control arms 18 extending radially therefrom, the arms being pivotally mounted on brackets 20 to swing inwardly and downwardly for folding. Each root portion 14 is secured across a part of its chord to one arm 18, the remainder of the chordal edge 22 extending unattached from the inboard end of that arm to the outer end of the next arm 18, with some fullness in the blade material to allow bowing of the chordal edge to form a gap 24 between said edge and the arm of the next blade, as in FIGURE 5. The outer edges of blades 12 are reinforced by cables 26 each extending from the tip of one blade to the inner junction at an arm 18 and out to the tip of the next blade. At the tip of each blade is a streamlined flyweight 28 with stabilizing fins 30, which can be adjusted to set the angle of incidence of the blade in operation, as hereinafter explained. Cables 26 are secured into the flyweights 28 and act as tension members to maintain the rotor configuration under centrifugal force, the cables being of wire, cord, or similar material according to strength requirements.

On the underside of hub 16 at the axis is a universal joint 32 to which is attached the upper end of a rotor shaft 34. To facilitate folding the shaft 34 has a suitable number of hinge joints 36, each comprising a connecting channel 38 in which sections 40 of the shaft are held by hinge pins 42. In folded position the shaft sections 40 are substantially parallel, as indicated in broken line in FIGURE 13,'but when the shaft is pulled out in a linear direction, the sections straighten out and a lock pin 44 is urged from one section by a spring 46 to enter the adjacent section and lock the two sections in axial alignment. For resetting and folding a retraction cord 48 is attached to each lock pin 44 and led outside the shaft section, so that the pin can be retracted and the sections folded. This hinge struc-' ture is merely an example and other arrangements may be equally suitable.

The lower end of shaft 34 is connected to a universal joint 50 at the axis of a control hub 52, which is freely axially rotatably mounted on a spindle 54 by means of bearings 56. Control hub 52 has a radical flange 58, below which are brackets 60 carrying spider arms 62 hinged to swing downwardly. Spider arms 62 and the pitch control arms 18 may be spring biased to the open position if required, but this is not essential. Each spider arm 62 is connected to one pitch control arm 18 by a pitch control cable 64, said spider arms being circumferentially dis: placed relative to the pitch control arms to provide the nec- '7 Q essary lead action in pitch control, as is well known in helicopter control technique. On the outer end of each spider arm 62 is an outer arm 66 mounted on a hinge pin 68 to swing in a radial plane perpendicular to the axis of control hub 52, when the spider arms are extended, as indicated in FIGURE 11, said outer arms being biased to the outwardly extended position by springs 70, or similar means, and held in that position by a stop 71. Each outer arm 66 has a vertical cross section of substantially airfoil shape inclined to serve as a vane 72 which, under the influence of air flow in the general direction of the rotor axis, will cause the rotor to spin. At the outer end of each outer arm 66 is a clevis 74 to which a shackle 76 is secured by a short tie cord 78, the shackle having a pivotal hook 80 which holds the end of one rotor blade 12 by engaging in a hold down ring 82 on the flyweight 28.

The control hub 52 has an axial post 84 on which are two rotatable drums 86 and 88 retained by a collar 89. From each hook 80 a restraining cable 90 extends through clevis 74 and through a guide 92 on flange 58, then is wrapped around andterminally secured to drum 86. On the periphery of drum 86 is a latching lug 49 which engages a latching cam 96 on a pre-load spring 98, so that a specific predetermined tension on restraining cables 90 will force said lug free of the cam and allow the cables to extend.

On each blade 12 a short distance inboard from the tip is a spreader bar 100 secured chordally between the cables 26, and secured to the spreader bar is a bridle 102 having a retaining ring 104. The bridle 102 is either of flexible material -or is flexibly attached to spreader bar 100, so that said bridle will lie flat along the blade when the rotor is extended and not interfere with rotor action. Engaging each ring 104 is a hook 106 pivotally mounted in a shackle 108, which is secured to collar 89 by a tie cord 110. From each hook 106 a restraining cable 112 extends through a guide 92, then is wrapped around and terminally secured to the drum 88. On the edge of drum 88 is a latching lug 114 which engages a latching cam 116 on a pre-load spring 118, the latter being stronger than spring 98 so that drum 88 requires more tension for release than drum 86, as will hereinafter be apparent. As illustrated the springs 98 and 118 are of the leaf type fixed at one end, with the other ends held by a key post 120. To facilitate initial or re-setting, the key post 120 is rotatably mounted in flange -8 and has a notch 122 into which the springs can drop to ease the pressure while the latching lugs and cams are engaged.

The rotor system described thus far can be used by suspending a payload from spindle 54, for simple vertical drop delivery in the manner of a parachute. The glide capability of the rotor, however, is best utilized by providing means to move the control hub axis while in operati'on.

Directional colntrol mechanism v The lower end of spindle 54 is attached to a pitch control arm 124 by a hinge pin 126, the arm, in turn, being pivotally mounted on a frame member 128 on a hinge pin 1'30 perpendicular to pin 126, so that the spindle is universally pivotal relative to said frame member. Pitch control arm 124 extends forwardly and is connected to a pitch control actuator 132 on frame member 128, while a roll control actuator 134 is coupled between said frame member and a roll control arm 136 projecting laterally from spindle 54.

In order to fold the unit as compactly as possible, frame member 128 is hinged to a bracket 138 on a base plate 140, to which the payload is attached. The frame member has a tongue 142 which is engaged and locked by a spring loaded latch 144 to hold the control mechanism upright when the assembly unfolds.

Various types of payloads can be attached to the base plate 140, that illustrated being a simple box type container 146, which can be a special container or the actual To prepare the rotor system for use the blades 12 are attached to hooks and 106 and the drums 86 and 88 are rotated to wind in the restraining cables and 112, the latching lugs 94 and 114 being engaged to hold the drums. Pitch control arms 18 are folded down and shaft 34 is folded at its respective joints. Outer arms 66 are swung inwardly and spider arms 62 folded down, the

rotor blades and various cables being neatly stowed in a suitable manner. Latch 144 is released so that frame member 128 can swing down and lower the collapsed rotor assembly still further. A cover or bag is then placed over the assembly and attached to the payload in any convenient manner, such as the flaps 152 held over small posts 154 and secured by quick release pins 156, as in FIGURE 1. Additional pins 156 can be used to hold the directional fins 148 folded. All release pins 156 are connected by pull cords 158 to a static line 160, which is also secured to the bag 150 and continues inside to a breakaway lanyard 162 terminally secured on rotor hub 16.

Other arrangements may be used to stow the rotor system, as a special compartment incorporated in the payload container, or a separate parachute-like package. The specific details will depend on the nature and size of the payload.

Deployment and operation The complete package ready for dropping is illustrated in FIGURE 1. Static line 160 can be anchored in the aircraft or may be connected to a small pilot parachute re leased in any suitable manner, both techniques being well known. As the package drops, the pull on static line 160 will tighten pull cords 158 and strip all release pins 156, allowing the bag 150 to pull free and fins 148 to extend. Continued pull on the static line will cause lanyard 162 to pull out the rotor assembly and unfold shaft 34 so that all the joints 36 snap into open and lock positions. Control hub 52 will swing up and latch 144 will secure the unit in place, the various hinged arms will open and extend the rotor in its initial form, the resultant configuration being shown in FIGURE 2. Lanyard 162 will then break away, as in the conventional static line extraction operation, leaving the rotor system and payload to continue in free fall. The air flow around the assembly, generally parallel to shaft 34, will act on vanes 72 and cause the rotor. assembly to spin about spindle 54. Air drag will tighten the flexible rotor blades 12 and how the root portions 14 to the extent of fullness in the material, the air flow escaping through gaps 24 and adding to the rotational elfect. In this initial mode the rotor acts in the manner of a small parachute to decelerate and stabilize the falling payload.

At a predetermined rate of rotation, the centrifugal spin force acting on flyweights 28 will overcome preload spring 98 and pull out the restraining cables 90 from drum 86.

Since shackles 76 are held back by tie cords 78 the inertia of flyweights 28 wil pull hooks 80 open to release rings 82. The blades 12 are still restrained by cords 112 to the bridles 102, but flyweights 28 will cause the tip portions, indicated at 164 in FIGURE 3, to extend laterally. Pins 30 on the flyweights are set to impart a slight angle of attack to the flyweights in relation to their plane of rotation, thus causing the blade tip portions 164 to assume a corresponding angle to the air flow .and act as small blades, so that the spin rate is increased. In this condition the major portion of the rotor is still in the drag parachute-like mode,

but rotational speed is increased rapidly and vertical descent is further retarded.

At a second predetermined rotational speed the centrifugal force of flyweights 28 is sufficient to overcome preload spring 118 and pull out restraining cords 112 from drum 88. Since shackles 108 are held by tie cords 110, the hooks 106 will open and release the bridles 162. With the considerable inertia built up by the preliminary spinning, the rotor blades 12 will extend to their full span, as in FIGURE 4, with an optimum rate of rotation already imparted. The setting of fins 30, which control the pitch of the blades, is such that a predetermined rate of descent is maintained, dependent on ultimate rotor rotational speed.

As a specific example of one rotor tested, the vanes 72 brought the rotor rapidly to about 300 r.p.m. at which speed the tip portions 164 extended. Rotation then increased to about 1000 r.p.m. when the blades were entirely released. Airflow speed was substantially less than that which would be encountered in free fall, but the rotor reached the required speeds rapidly and remained stable throughout the sequence. The shackles are extended to the limits of their tie cords by centrifugal force, but do not interfere with the rotor operation.

To control the direction of descent the control hub 52 is operated somewhat in the manner of a swash plate in a helicopter rotor. The fins 148 establish a forward direction and the assembly will glide in that direction rather than falling vertically. In fact the rotor may be initially rigged to apply a forward moment to the assembly in normal rotation. Actuators 132 and 134 are operated to incline the control hub 52 which, through the pitch control cables 64, imparts cyclic pitch changes to the rotor blades and causes the rotor plane of rotation, or the effective thrust axis, to become offset in the required direction to change the path of descent. The pitch change is effective primarily on the inboard portions of the blades, since the outer portions are stabilized by centrifugal action, but the aerodynamic forces developed are ample for directional control and for longitudinal or glide path control by varying the eflective lift action of the blades. The operating means for the actuators will depend on the type of actuators used and could be a simple stored supply of electrical, fluid, vor mechanical power suflicient for the duration of descent, the control forces involved being very small. Directional control could be achieved by remote radio control, a programmed pattern incorporated into the system, or other such means. Swash plate type control systems and remote or programmed operating means are well known in many different forms and the present rotor system is not limited to any particular arrangement.

As an additional protection for the payload a ground contacting device 166 may be suspended from the payload, as indicated in FIGURE 15, to trip a flare-out actuator 168 and operate pitch control actuator 132. When the payload is at a predetermined short distance from the ground, the rotor will then be flared to provide a sudden increase in lift and a deceleration, so that the final settling of the payload is at a predetermined short distance from the ground, the rotor will then be flared to provide a sudden increase in lift and a deceleration, so that the final settling of the payload is very gentle. Such systems are also known, a particular example being given in US. Patent No. 3,102,703. The mechanism therein is applied to a flexible wing, but the general action and end result is the same as that of the flare-out of the present rotor.

The sequential opening of the rotor into an intermediate parachute-like mode with the blades restrained and the subsequent two stage spin-up process greatly reduce shock loads on the rotor and payload, and also reduce the magnitude and rapidity of inertial changes in rotor rotation from the initial to fully open positions. Due to the unique physical and dynamic characteristics of the fully flexible blades, a direct transition from folded to open position is impractical, the preliminary spin-up being necessary to provide centrifugal inertia to ensure autorotation when the blades extend. After extraction of the rotor from its pack the entire spin-up and opening sequence is perforned by surrounding airflow and centrifugal force, no timers, power sources, or explosive devices being needed. Consequently the system can be used under widely varying conditions with a minimum of maintenance.

It is understood that minor variation from the form of the invention disclosed herein may be made without departure from the spirit and scope of the invention, and that the specification and drawings are to be considered as merely illustrative rather than limiting.

I claim:

1. A rotor system for air to surface delivery of a payload, comprising:

an attachment member having means for attachment to a payload;

a rotor mounted for free rotation relative to said attachment member and having flexible blades;

restraining means for holding tip portions of said blades adjacent the axis of rotation in a partially open position;

spin inducing means coupled to said rotor to spin the rotor with the blades in said partially open position;

and rotation responsive release means coupled to said restraining means to release said blades at a predetermined rate of rotation, whereby the blades extend centrifugally.

2. A rotor system according to claim 1, wherein said spin inducing means includes vanes coupled to said blades and exposed to air flow around the rotor during descent.

3. A rotor system according to claim 1 and including flyweights attached to the outer tips of said blades, said flyweights having fins aligned relative to the blades to maintain a predetermined pitch angle of the blades during rotation.

4. A rotor system according to claim 1, and including further restraining means releasably connected to said blades inboard of the tips thereof;

and further rotation responsive release means coupled to said last mentioned restraining means to release the same at a second predetermined rate of rotation higher than the first mentioned rate.

5. A rotor system according to claim 1 and including control means coupled to said rotor to vary the effective thrust and thrust axis thereof.

6. A rotor system according to claim 5 and including directional stabilizing fin means fixedly mounted relative to the payload.

7. A rotor system for air to surface delivery of a payload, comprising:

an attachment member having means for attachment to a payload;

a control hub freely rotatably mounted on said attachment member;

a shaft having its lower end secured to said control hub;

a rotor, including a hub secured to the upper end of said shaft and a plurality of flexible blades connected to said hub;

restraining means on said control hub for holding the outer tips of said blades adjacent the control hub in a partially open position;

spin inducing means coupled to said rotor to spin the rotor with the blades in said partially open position;

rotation responsive release means coupled to said restraining means to release said blades at a predetermined rate of rotation;

and directional control means coupled to said motor to vary the effective thrust axis of the rotor.

8. A rotor system for air to surface delivery of a payload, comprising:

an attachment member having means for attachment to a payload;

a control hub freely rotatably mounted on said attachment member;

a shaft having its lower end secured to said control hub;

a rotor, including a hub secured to the upper end of said shaft and a plurality of flexible blades connected to said hub;

fiyweights attached to the outer tips of said blades, said fiyweights having fins aligned relative to the blades to maintain a predetermined pitch angle of the blades during rotation;

restraining means on said control hub for holding the outer tips of said blades adjacent the control hub in a partially open position;

spin inducing means coupled to said rotor to spin the rotor with the blades in said partially open position;

rotation responsive release means coupled to said restraining means to release said blades at a predetermined rate of rotation;

and control means coupled to said rotor to vary the effective thrust and thrust axis of the rotor.

9. A rotor system according to claim 8 and including further restraining means on said control hub having releasable means for attachment to said blades inboard of the tips, whereby the tip portions only of said blades are released by said first mentioned release means, so that the tip portions extend and constitute additional spin inducing means;

and further rotation responsive release means coupled to said last mentioned restraining means to release said blades at a higher rate of rotation than said first mentioned release means.

10. A rotor system according to claim 8, wherein said control means includes pitch control arms pivotally mounted on said rotor hub, each being attached substantially chordally to one of said blades;

spider arms extending from said control hub;

control means connecting each of said spider arms with one of said pitch control arms;

said rotor hub and said control hub being universally pivotally connected to said shaft;

and actuating means to incline said control hub relative to the axis of said shaft.

11. A rotor system according to claim 8 wherein said spin inducing means comprises vanes on said spider arms exposed to air flow around the rotor.

12. A rotor system according to claim 8 wherein said shaft has foldable joints and said pitch control arms and said spider arms are foldable;

and including extraction means connected to said rotor to extend said shaft and open said rotor to said partially open position when the rotor is air dropped.

References Cited UNITED STATES PATENTS.

2,776,017 1/1957 Alexander -16011 3,057,589 10/ 1962. Nutkins et a1. 294-438 3,117,630 1/1964 Barish 170-16011 3,150,850 9/1964 Barish 170l60;11 X 3,188,020 6/1965 Nielsen et al. 170160.12 X

MARTIN P. SCHWADRON, Primary Examiner.

EVERETTE A. POWELL, 111., Examiner. 

1. A ROTOR SYSTEM FOR AIR TO SURFACE DELIVERY OF A PAYLOAD, COMPRISING: AN ATTACHMENT MEMBER HAVING MEANS FOR ATTACHMENT TO A PAYLOAD; A ROTOR MOUNTED FOR FREE ROTATION RELATIVE TO SAID ATTACHMENT MEMBER AND HAVING FLEXIBLE BLADES; RESTRAINING MEANS FOR HOLDING TIP PORTIONS OF SAID BLADES ADJACENT THE AXIS OF ROTATION IN A PARTIALLY OPEN POSITION; SPIN INDUCING MEANS COUPLED TO SAID ROTOR TO SPIN THE ROTOR WITH THE BLADES IN SAID PARTIALLY OPEN POSITION; AND ROTATION RESPONSIVE RELEASE MEANS COUPLED TO SAID RESTRAINING MEANS TO RELEASE SAID BLADES AT A PREDETERMINED RATE OF ROTATION, WHEREBY THE BLADES EXTEND CENTRIFUGALLY. 